The introduction of optical frequency references, atom interferometry, as well as of optical ranging and communications, creates new opportunities for systems based on time and frequency dissemination. The project investigates innovative architectures for a future satellite system that fully exploits the benefits of each of the aforementioned technologies. The architecture shall be based on a satellite constellation, named Kepler, divided into two segments: twenty-four Medium-Earth-Orbit (MEO) satellites and at least four Low-Earth-Orbits (LEO) satellites. MEO satellites shall be equipped with laser-stabilized cavities, characterized by Allan deviations down to 1e-14 and beyond for short integration time intervals, whereas LEO satellites shall be equipped with stable optical references (e.g. Iodine-based optical clocks). Optical terminals placed on each satellite will allow inter-satellite links (ILS), enabling tight intra- and inter-plane synchronization across the whole constellation, and providing absolute (sub-mm) inter-satellite ranging.

Global navigation satellite systems (GNSS) have been identified as primary means of navigation for aeronautics in the future and enable efficient procedures. But GNSS is vulnerable to radio frequency interference and space weather. The project Alternative Positioning System (ALPS) develops an alternative positioning navigation and timing system, composed of different terrestrial systems and on board sensors to function as a backup in case of a GNSS outage.

Civil aviation is an important asset of today’s mobile society and belongs to the critical infrastructures. Thus, the protection of civil aviation is of high importance to society.
In aviation, economic pressure requests cost reductions and improved efficiency in handling aircraft. As a consequence, the infrastructure and technical systems become more and more interconnected to save costs through re-use of resources and exploitation of synergies. Besides these desired effects, the interconnection of formerly separate technical systems generates new risks. These risks are especially caused by threats from cyberspace. Main goal of the project ARIEL is to perform a holistic risk analysis and evaluation of critical infrastructures in aviation, since these might become the target of sophisticated cyberattacks to create new threats to public safety and security.

Leading principle during navigation of vessels is the avoidance of collision and groundings to protect life, goods, and the maritime living space. However, a virtually unchanged number of ships’ accident has been observed during the last decade. Statistical analyses show that more than 50% of ship collisions have navigational causes, whereby 65% of whom has been induced by human factor. Main reasons in this context are insufficient situation monitoring (28%), misleading evaluation of ships’ motion (17%) as well as fatigue and overstressing of nautical staff (13%). The risk on incorrect decisions and therewith the risk on accidents can be reduced by application of automated assistance functions supporting the seafarer in situation monitoring, evaluation, and decision finding.

Laser communication through the atmosphere is impaired by turbulences in the atmosphere. This effect, known as scintillation, causes fades in the received power and outages in the laser communication for several milliseconds. Due to the high data rate in the order of 1 Gbit/s and beyond, bit error bursts of 1 Mbit and more can be observed. To compensate for this effect, DLR developed a packet level coding scheme, whose code words are longer than such error bursts and thus able to correct the long error bursts in the best possible way without the need of an interleaver. The objective of the project COLT is to design, implement and demonstrate a FPGA based packet level coder and decoder for data rates of about 1 Gbit/s.